1. Technical Field of the Invention
The invention generally relates to the field of selectively removing and recovering lithium from solution. More particularly, the invention relates to methods and compositions for the selective removal and recovery of lithium ions from a lithium ion containing solution, preferably without the removal of measurable quantities of other ions from the solution, in particular as related to lithium containing brines.
2. Description of the Prior Art
Approximately 75 to 80% of lithium chloride and lithium carbonate and their derivatives are commercially produced from the recovery of lithium from brines, typically via natural evaporative processes. The invention described herein is applicable to these and other brine sources. The invention described herein is also equally applicable to high ionic strength solutions that include lithium.
Geothermal brines are of particular interest for a variety of reasons. First, some geothermal brine provide a source of electrical power due to the fact that hot geothermal pools are stored at high pressure underground, which when released to atmospheric pressure, can provide a flash-steam. The flash-stream can be used, for example, to produce energy to run a power plant. In some geothermal waters and brines, associated binary processes can be used to heat a second fluid, which can provide steam for the generation of electricity without the flashing of the geothermal brine. Additionally, geothermal brines contain various useful elements, which can be recovered and utilized for secondary processes.
It is known that geothermal brines can include various metal ions, particularly alkali and alkaline earth metals, as well as transition metals such as lead, silver, manganese and zinc, in varying concentrations, depending upon the source of the brine. Recovery of these metals is potentially important to the chemical and pharmaceutical industries. Typically, the economic recovery of metals from natural brines, which may vary widely in composition, depends not only on the specific concentration of the desired metal, but also upon the concentrations of interfering ions, particularly silica, calcium and magnesium, because the presence of the interfering ions will increase recovery costs as additional steps must be taken to remove the interfering ions.
As lithium has gained importance as an element for use in various applications, such as for use in batteries, research has been conducted to develop simple and inexpensive methods for the recovery thereof. For example, Burba previously developed two- and three-layer lithium aluminates for the recovery of lithium from brines. (See, for example, U.S. Pat. Nos. 4,348,295 and 4,461,714). The prior art methods that employ packed columns for the recovery, however, suffer from many drawbacks, such as shortened lifetimes due to the slow deterioration and disintegration of the particles and an overall low operating capacity for the removal of lithium.
Thus, there exists the need for the development of new and improved synthetic methods and materials for the selective and efficient recovery of lithium from lithium containing brines (i.e., recovery of at least about 95% of the lithium present in a solution) that are easy to use, have a high capacity for the recovery of lithium, and have a long service life.